Thesis advisor: Clare O'Connor / Telomeres are repeated sequences at the ends of chromosomes, which promote chromosome stability by preventing the loss of necessary nucleotides from the DNA with successive rounds of replication. Telomeres are elongated by the enzyme telomerase, which has both a protein component and an RNA component. In the yeast Saccharomyces cerevisiae, the TLC1 gene encodes the RNA component of the enzyme. Telomerase RNA interacts with several proteins to perform its function, including the Ku protein, which binds to the end of the DNA and helps to recruit telomerase to the chromosome thereby facilitating the lengthening of chromosome ends. Ku interacts with telomerase RNA at the site of a 48-nucleotide stem-loop on the RNA's structure. Previous experiments have shown that yeast strains engineered to carry two copies of the TLCI gene exhibit higher levels of telomerase RNA than those that have only one copy of the gene. Also, a yeast strain carrying a copy of the mutant tlc1Δ48 gene, which contains a deletion of the 48-nucleotide stem-loop, contains lower levels of telomerase RNA than a strain with the wild type TLC1 gene. This series of experiments is investigating whether the copy number of the telomerase RNA gene affects the elongation of telomeres in S. cerevisiae. In order to determine this effect, the de novo telomere addition of four strains was examined, as were the native telomere lengths of these strains. The assay indicated that the efficiency of telomere elongation was unchanged by increasing the copy number of the wild type gene but was increased upon increasing the copy number of the mutant gene. Analysis of the native telomere lengths showed that increasing the copy number of either the wild type or the mutant gene allowed the cells to maintain their telomeres at a longer length. / Thesis (BS) — Boston College, 2008. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Biology. / Discipline: College Honors Program.

Introdução: O comprimento telomérico é estudado em vários processos da relação saúdedoença, tais quais estresse oxidativo, processo inflamatório e estresse crônico e parece ser modulado por fatores genéticos e ambientais, além de estar associado a doenças como aterosclerose, doença de Alzheimer, insuficiência cardíaca e disqueratose congênita. Nosso estudo buscou entender a relação entre os telômeros de recém-nascidos e a gestação sob condições adversas. Objetivo: avaliar o impacto da exposição a diferentes ambientes intrauterinos sobre o comprimento de telômeros dos recém-nascidos. Métodos: o comprimento telomérico foi avaliado através do método de qPCR (Razão T/S) de células da mucosa oral de uma amostra conveniência de 239 pares de mãe e recémnascido, divididos nos seguintes grupos de mães: diabéticas (DM) (n=39), hipertensas (HAS) (n=16), tabagistas (n=52), controle (n=99) e mães que tiveram filhos pequenos para a idade gestacional (PIG) (n=33). Resultados: Em todos os grupos observamos uma correlação fraca entre o comprimento telomérico da mãe e da criança (r= 0,229) (p<0,001). Não houve diferença significativa no comprimento telomérico entre os grupos DM, HAS, PIG, Tabaco e Controle. Entretanto, dentro do grupo Tabaco houve diferença significativa numa relação dose-resposta inversa, de maior consumo de cigarro e comprimento telomérico menor, tanto para a mãe (p=0,020) quanto para o recém-nascido (p=0,033). Conclusão: os achados deste estudo sugerem que o uso do tabaco na gestação pode exercer influência negativa sobre o comprimento dos telômeros tanto da mãe quanto do seu filho. / Background: Telomere lenght has been studied in several health-disease processes, such as oxidative stress, inflammatory process and chronic stress. It seems to be influenced by genetic and environmental issues, and it is associated with diseases such as atherosclerosis, Alzheimer's disease, heart failure and congenital dyskeratosis. Our study searched to understand the relationship between newborns telomeres and adverse intrauterine conditions. Objective: to evaluate the impact of exposure to different intrauterine environments on the telomere length of newborns. Methods: the telomere length was evaluated by qPCR (T/S ratio) on oral mucosa cells of a convenience sample of 239 pairs of mother and newborn, divided according to the following groups of mothers: diabetic (DM) (n = 39), hypertensive (HAS) (n = 16), tobacco (n = 52), controls (n = 99) and mothers who had small children for gestational age (SGA) (n = 33). Results: In all groups we observed a weak correlation between the telomere of the mother and the son (r= 0.229) (p <0.001). There was no significant difference in telomere size between DM, HAS, SGAG, Tobacco and Control groups. However, in the Tobacco group there was a significant difference in an inverse dose-response relationship: higher cigarette consumption and lower telomere length, both for the mother (p = 0.020) and for the newborn (p = 0.033). Conclusion: the findings of this study suggest that tobacco use during gestation may induce a negative influence on the telomere length of both the mother and her child.

Background & Objectives: This dissertation is comprised of two independent projects that seek to answer the research questions outlined in Aims 1 and 2. The first project is focused on measuring exposure to polybrominated diphenyl ethers (PBDE) throughout the early lifecourse, as well as investigating how exposure at different developmental periods relates to neuroendocrine endpoints. PBDEs are flame retardant chemicals that were used extensively in furniture and furnishings sold throughout the United States until their phase-out in 2004. Human exposure occurs primarily through incidental ingestion of PBDE-contaminated dust present in the indoor environment. The second project aimed to characterize telomere dynamics in maternal-child pairs and to evaluate associations between telomere dynamics and indicators of stress and stressful conditions. Telomeres are non-coding nucleotide repeats located at chromosome ends; they serve several functions, such as buffering against loss of important protein coding DNA regions during cell division. Both projects are focused on exposure-response relationships during early life and a central theme throughout this dissertation relates to the intersection of date, time and age in longitudinal cohort studies. Finally, the third aim seeks to integrate findings from Projects I and II and is focused on investigating whether telomere dynamics can be used as a biological indictor of stress in epidemiological research examining associations between low-level environmental chemical exposures and neurodevelopmental endpoints. Methods: Both projects were conducted using data and samples collected as part of the Columbia Center for Children’s Environmental Health (CCCEH) Mothers and Newborns study. In Project I, PBDEs were measured by the Centers for Disease Control and Prevention (CDC) using gas chromatography-mass spectrometry (GC-MS) in plasma samples collected repeatedly between birth and age 9 years. We examined determinants of 1) prenatal exposure to PBDEs (Chapter 2), and 2) trajectories of PBDE exposure over childhood, which we estimated using latent class growth analysis (LCGA) (Chapter 3). We also examined PBDE trajectories in relation to performance on tests of visual, verbal and working memory among early adolescents (Chapter 4) and investigated associations between prenatal exposure to PBDEs and thyroid hormone parameters, which were measured by radioimmunoassay in plasma samples collected at multiple ages (Chapter 5). In Project II, we used monochrome multiplex quantitative polymerase chain reaction (MMqPCR) to measure relative leukocyte telomere length (rLTL) in samples collected from mothers and newborns (umbilical cord blood) at the child’s delivery and from children at ages 2, 3, 5, 7 and 9-years (Chapter 6). We aimed to characterize rLTL dynamics over early life, examine the correlation between paired maternal-newborn rLTL, and examine associations between rLTL with measures of financial strain, perceived stress and maternal distress. Results: In Project I, we detected PBDEs in over 80% of cord blood samples and in multivariable models, sociodemographic and lifestyle factors explained 12% of cord blood PBDE variability. The largest determinant of exposure was ethnicity, with Dominican newborns having lower exposure compared to African American newborns, likely due to the reduced amount of time Dominican mothers had spent in the United States when they gave birth to the study child. Across postnatal life (2000 to 2013), PBDE concentrations in child blood decreased by approximately 12% per year, suggesting that exposure has continually declined since the PBDE phase-out in 2004. Trajectory analyses revealed several unique patterns of PBDE exposure over the early lifecourse, with the majority of children characterized by exposure that was persistently low or that peaked during toddler years. Smaller groups of children were characterized by exposure that was highest during the prenatal period and decreased after birth or by a pattern of high exposure during toddler years that remained elevated into middle childhood. We identified several important predictors of childhood PBDE exposure patterns, including modifiable factors, such as cleaning behaviors. In relation to neurodevelopmental outcomes, we found that children with sustained high exposure to PBDEs scored approximately 5-8 points lower on tests of visual memory. Associations between prenatal exposure and working memory significantly varied by sex, with inverse associations (approximately 8 points lower) observed only among girls. Children with PBDE plasma concentrations that peaked during toddler years performed better on verbal domains, however, these associations were significant only among children breastfed for more than 12 weeks. Finally, in relation to thyroid hormone levels, children with BDE-47 concentrations in the third and fourth quartiles of the exposure distribution (versus first quartile) had significantly lower TSH and free T4 levels, respectively. We did not detect associations between BDE-47 and total T4 levels; likewise, we did not detect associations between other pentaBDE congeners and any thyroid parameter. In Project II, we found that maternal-newborn rLTL in paired samples was moderately correlated and that maternal rLTL at delivery explained 8% of the variability (R2) in newborn rLTL. In relation to measures of hardship, perceived stress and demoralization, we found an inverse, albeit not statistically significant, association between maternal perceived stress and newborn rLTL. We did not detect an association with maternal rLTL, nor did we detect associations between material hardship or demoralization and maternal or newborn rLTL. When examining rLTL in child blood samples collected between birth and age 9 years, we observed a U-shaped pattern characterized by rapid shortening of rLTL between birth and 2 years, followed by gradual lengthening between ages 3 and 9 years. It remains unresolved whether this pattern reflects a true biological phenomenon or if it is an artifact of measurement error introduced by analytic or pre-analytic conditions. Conclusions: Despite the phase-out of PBDEs in 2004, exposure among children residing in New York City remained nearly ubiquitous through 2013, however, concentrations did decline over time. Our finding of several PBDE trajectories suggests that, despite the relatively long half-lives of PBDEs, a single measure may not accurately reflect exposure throughout childhood. Our findings of reduced scores on tests of working and visual memory during the prenatal and postnatal periods, respectively, support a growing body of literature linking early life PBDE exposure to disrupted neurodevelopment. The results of our analysis examining thyroid hormone disruption during childhood revealed a pattern consistent with hypothalamic or pituitary-level disruption during prenatal programming of the thyroid regulatory system. This is the first study to examine prenatal PBDE exposure in relation to childhood thyroid hormone levels, therefore, it is important that this finding is replicated by future research. Our finding of an inverse association between newborn rLTL and maternal perceived stress is consistent with results from previous research and suggests that the developing fetus may be sensitive to maternal stress perception during pregnancy, however, additional research is needed to more fully understand the mechanisms through which this transmission occurs. Our finding of increasing telomere length between toddler years and middle childhood is unexpected and raises questions about the suitability of the qPCR assay for analyzing telomere length in archived samples. Additional analyses are needed to determine whether the observed patterns reflect true biological changes or relate to measurement error introduced during sample processing, storage or analysis. Given these outstanding issues, we were ultimately unable to draw conclusions about the usefulness of telomere dynamics as a stress-sensitive biomarker.

Telomeres are increasingly used as biomarkers of somatic maintenance and could conceivably play a causal role in life history trade-offs. In this thesis, I use longitudinal telomere measures from a wild population of cooperatively breeding white-browed sparrow weavers (Plocepasser mahali) to further our understanding of the causes and fitness consequences of individual variation in somatic maintenance, with particular focus on hitherto unexplored effects of the social environment. In Chapter 2, I start by investigating the key prediction of life-history theory that shortfalls in somatic maintenance in early life entail later-life costs, and find supporting evidence. Nestlings with higher within-individual rates of telomere attrition show reduced survival to the following season, even after controlling for the effects of variation in body mass. In Chapter 3, I then investigate the effects of the social and abiotic environment on nestling telomere length and attrition rates and find the first support, to my knowledge, for the key prediction that helpers in cooperatively breeding societies alleviate telomere attrition rates in growing offspring (consistent with the expectation that helper contributions to nestling feeding relax resource allocation trade-offs in offspring). In addition, I find that rainfall prior to egg-laying has a positive effect on hatchling telomere length; an effect that most likely arises via egg- or incubation-mediated maternal effects. In Chapter 4, I investigate the causes of variation in telomere attrition rates in adults, and while there are no overall differences in telomere length or long-term within-individual telomere dynamics between dominant and subordinate birds, my findings are suggestive of dominance-related differences in the short-term regulation of telomere length. In addition, and in concordance with predictions of life-history theory regarding trade-offs between somatic maintenance and reproduction, I find that annual rainfall (a proxy for reproduction-related activity during the breeding season) negatively predicts the within-individual rate of change in telomere length in adults specifically over the breeding season; there was no such relationship in the non-breeding season. Finally, in Chapter 5, I investigate the extent to which natural variation in oxidative state predicts variation in within-individual rates of change in telomere length over time. This chapter provides evidence suggestive of associations between oxidative state and telomere dynamics in a natural population, and highlights complexity in the nature of these relationships. Together my findings provide novel support for key predictions of life-history theory regarding the causes and consequences of variation in somatic maintenance, and lend strength to the view that longitudinal field studies of telomere dynamics can offer useful insights in this regard. Furthermore, my findings highlight the potential for diverse effects of the social environment on patterns of somatic maintenance, and specifically hitherto unexplored downstream effects of helping behaviour on later-life performance and ageing trajectories.

Transtornos mentais graves são doenças crônicas altamente incapacitantes que geram um alto custo para a sociedade. Indivíduos acometidos por essas doenças apresentam maior morbidade e mortalidade. Dentre elas, a esquizofrenia parece possuir os piores desfechos. Portanto, estudar a esquizofrenia pode trazer contribuições importantes para o entendimento e manejo de transtornos mentais graves como a depressão maior e o transtorno bipolar. Esse trabalho buscou compreender mecanismos fisiopatológicos da esquizofrenia ao longo de quatro artigos que exploram aspectos de funcionamento cognitivo, funcionamento intelectual, de biomarcadores e de estrutura cerebral. O primeiro artigo investigou as alterações de performance de memória em indivíduos com esquizofrenia em estágios iniciais e tardios da doença comparadas ao transtorno bipolar e a sujeitos saudáveis. Os resultados mostraram que indivíduos com esquizofrenia apresentaram precoces prejuízos cognitivos de memória, diferentemente de indivíduos com transtorno bipolar quando comparados a controles. O segundo artigo investigou as influências das performances cognitiva e intelectual em estruturas cerebrais de indivíduos com esquizofrenia comparados a controles saudáveis. Os resultados indicaram que o funcionamento intelectual pré-morbido estava relacionado ao volume de estruturas globais, enquanto o funcionamento cognitivo estava relacionado ao volume e espessura de massa cinzenta cortical, sugerindo influências diferentes e complementares relacionadas a neurodesenvolvimento e neurodegeneração. O terceiro artigo investigou um biomarcador de envelhecimento precoce, um possível mecanismo para a neuroprogressão na esquizofrenia. Os resultados monstraram que indivíduos com esquizofrenia apresentaram encurtamento de telômero quando comparados a controles, mas não houveram diferenças entre o tamanho de telômero de pacientes e seus irmãos não afetados pela doença. Por fim, o quarto artigo buscou investigar a teoria do envelhecimentoa patológico acelerado na esquizofrenia, integrando os achados dos artigos anteriores. Os resultados demonstraram correlações entre comprimento de telômero, níveis de CCL11, performance de memória, volume de massa cinzenta e tempo de doença em indivíduos com esquizofrenia. Esses achados sugerem que a esquizofrenia seria uma doença do neurodesenvolvimento associada a uma carga adicional ao longo do curso da doença que levaria a um envelhecimento patológico precoce. A partir dos achados em esquizofrenia, pode-se ampliar a compreensão de alterações percebidas nas trajetórias de outras psicopatologias. Com adequado entendimento desses mecanismos, será possível o desenvolvimento de novos tratamentos e intervenções mais efetivas e eficazes. / Severe mental disorders are debilitating chronic diseases that have a high cost to society. Individuals affected by these diseases have increased morbidity and mortality. Among them, schizophrenia seems to have the worst outcomes. Therefore, studying schizophrenia may provide important contributions to the understanding and management of severe mental disorders such as major depression and bipolar disorder. The present study aimed to understand the pathophysiological mechanisms of schizophrenia over four articles that explore aspects of cognitive functioning, intellectual functioning, biomarkers and brain structure. The first article investigated changes in memory performance in individuals with schizophrenia in early and late stages of disease compared to bipolar disorder and healthy subjects. The results showed that subjects with schizophrenia had early cognitive deficits of memory, unlike individuals with bipolar disorder compared to controls. The second article investigated influences of cognitive and intellectual performances on brain structures of individuals with schizophrenia compared to healthy controls. The results indicated that premorbid intellectual functioning was related to volume of global structures, while cognitive functioning was related to volume and thickness of cortical gray matter, suggesting different and complementary influences related to neurodevelopment and neurodegeneration. The third article investigated an early aging biomarker, a possible mechanism of neuroprogression in schizophrenia. The results showed that individuals with schizophrenia had shortened telomeres when compared to controls, but there were no differences between the telometer length of patients and their siblings not affected by the disease. Finally, the fourth article sought to investigate the theory of pathological accelerated aging in schizophrenia, integrating the findings of the previous articles. The results demonstrated correlations between telometer length, CCL11 levels, memory performance, gray matter volume and illness duration in individuals with schizophrenia. These findings suggest that schizophrenia is a neurodevelopmental disorder associated with an additional burden over the course of the disease that leads to a pathological accelerated agig.

Orientador: Maria Isabel Nogueira Cano / Resumo: Os protozoários do gênero Leishmania causam leishmaniose, uma doença tropical negligenciada, que se apresenta de diferentes formas clínicas e que acomete milhões de pessoas no Brasil e no mundo. Até o momento não existe nenhuma vacina ou tratamento eficientes para leishmaniose e por isso, estudos que contribuam para o entendimento da biologia e fisiologia do parasito podem fornecer uma possibilidade de encontrar novos alvos terapêuticos. Este é o caso dos telômeros, cuja função principal é manter a estabilidade do genoma que se perturbada pode afetar diretamente a proliferação ou multiplicação dos parasitos. Os telômeros são estruturas nucleoprotéicas localizadas nas extremidades dos cromossomos, mantidos pela enzima telomerase. Eles são regulados por diversos processos entre os quais se encontram alguns longos RNAs não codificadores (lncRNA). Entre os lncRNAs com função telomérica está o TER (RNA Telomerase) o qual é um dos principais componentes do complexo telomerase, pois contém uma pequena sequência molde a qual é copiada pela telomerase durante a replicação dos telômeros, o TER foi recentemente identificado em Leishmania spp., porém se desconhece a sua função e biogênese. Outro RNA não codificante com função telomérica é o TERRA (Repetições Teloméricas contendo RNA), os quais são essenciais para a manutenção dos telômeros. Até o momento, identificamos a presença do TERRA expressos a partir das extremidades cromossômicas nas diferentes fases de desenvolvimento (amastigot... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Protozoan from Leishmania genus are the etiologic agents of leishmaniasis, a tropical disease that presents different clinical manifestations and affect million people in Brazil and in the world. There are no eficiente vacines nor treatment protocols against leishmaniasis, therefore, it is crucial to improve the knowledge about Leishmania molecular biology and physiology for the development of new therapies. Actually, telomeres have been considered potential molecular targets as they are responsible to maintain genome stability. Leishmania telomeres similarly to other eukaryotes, are nucleoprotein structures found at the end of the chromosomes maintained by telomerase. They can be regulated by different mechanisms such as the action of long non-coding telomeric RNAs (lncRNAs). Among the telomeric lncRNAs are the telomerase RNAcomponent (TER) which is crucial for telomerase activity because it contains the template sequence that is copied by telomerase during telomere elongation. TER was recently identified in Leishmania although there is no information about its function and biogenesis.TERRA, the Telomere Repeat containing RNA is other telomeric RNA that it is involved with telomere length regulation telomere damage response and alterations in the composition of telomeric chromatin and is essential for telomere maintenance. In this work, we identified TERRA transcripts in the three Leishmania developmental stages (amastigote, promastigote e metacyclic). We interrogate three i... (Complete abstract click electronic access below) / Doutor

Imunossenescência, termo que designa o envelhecimento do sistema imune, contribui com o aumento das infecções, doença autoimune, câncer e baixa eficiência das vacinações, favorecendo o aumento da morbi-mortalidade entre os indivíduos idosos. Dentre as mudanças, destacam-se as alterações no tamanho da subpopulação de célula T, com aumento de células de memória e diminuição de células naive; no padrão de secreção de citocinas, na capacidade de replicação das células e na produção de anticorpos, as quais culminam em um estado pró-inflamatório chamado \'inflamm-aging\' e uma capacidade diminuída para responder a novos antígenos. Além disto, o acúmulo de linfócitos T CD8+CD28- nos idosos também se correlaciona com uma diminuição do controle sobre a infecção. No entanto, há poucos relatos sobre o papel do exercício regular na prevenção ou tratamento de imunossenescência. O objetivo deste estudo foi verificar os efeitos da atividade física intensa e regular na imunossenescência de idosos. Foram selecionados 15 indivíduos idosos em treinamento intenso de corrida (meia maratona e/ou maratona há pelo menos 5 anos, TI), e 16 indivíduos idosos não praticantes de atividade física, NT. Todos os indivíduos eram do sexo masculino, com idade entre 65 a 85 anos, apresentavam auto percepção de saúde positiva e ausência de co-morbidades e/ou em tratamento com impacto significativo para o sistema imune. Foram avaliadas as subpopulações de células T (CD8+CD28+ e CD8+CD28-; CD4+ naive e de memória) em relação ao comprimento de seus telômeros, resposta proliferativa e marcadores de apoptose, síntese de citocinas (Th1/Th2); níveis séricos de citocinas inflamatórias; frequência das subpopulações (naive, memória central, memória efetora e terminalmente diferenciada) dos linfócitos T CD4+ e CD8+ no sangue periférico e a quantificação da produção de anticorpos anti-Influenza. Verificamos no grupo TI, em relação ao NT, aumento de células TME e diminuição de TEMRA; maior proliferação de linfócitos T CD4+ naive estimulados com mitógeno; maior comprimento do telômero em linfócitos T CD3+, T CD3+CD8+ e T CD3+CD8+CD28-, esta última considerada subpopulação associada à imunossenescência; preservação dos mecanismos anti-apoptóricos, verificado pelo aumento da expressão in vitro de Bcl-2 e redução de caspase-3 em células TCD4+ (memória e naive) e T CD8+ (senescentes e não senescentes) não estimuladas; parâmetros estes denotando uma provável melhor capacidade funcional de células T. Além disso, verificamos aumento da produção sérica de títulos de anticorpos anti-influenza pré e pós-vacinação, evidenciando possível papel adjuvante do exercício intenso na resposta vacinal. E finalmente, observamos equivalência entre os dois grupos com relação ao padrão de secreção de citocinas séricas e secretadas in vitro associadas com o Inflammaging. Os resultados evidenciaram que a prática da atividade física intensa e regular teria um efeito protetor contra alguns parâmetros associados à imunossenescência / Immunosenescence, the term used to designate the process of aging of the immune system, is associated with to the increased rate of infections, autoimmune diseases, cancer and low efficiency of vaccinations in elderly, favoring their increased morbidity and mortality. Immunosenescence is associated with changes in the size of the T cell subpopulation with increased proportion of memory T cells and decrease proportion of naive T cells, in the pattern of cytokine secretion, in cell replication capability and in antibody production, all of which culminate in a pro-inflammatory state called \"inflamm-aging\" and diminished capacity to responding to new antigens. In addition, the accumulation of CD8+CD28- lymphocytes in elderly also correlates with a decreased control of infections. However, there are few reports on the role of chronic regular exercise in the prevention or treatment of immunosenescence. The objective of this study was to investigate the effects of intense regular physical activity on immunosenescence of elderly men. We selected 15 elderly men with intensive training for at least the last 5 years (IT, participating in half marathon and/or marathon), and 16 elderly men not training, NT. They were 65-85 years and had self perception of positive health and lack of co-morbidities and/or treatment with significant impact on the immune system. T-cell subpopulations were assessed (CD8+CD28+ and CD8+CD28-; CD4+ naive and memory) with respect to telomere length, proliferative responses, apoptosis markers, cytokine synthesis (Th1/Th2); serum levels of inflammatory cytokines; distribution of the naive, central memory, effector memory, and terminally differentiated CD4+ and CD8+ lymphocyte subpopulations in peripheral blood, and anti-influenza antibodies production. We found in the IT group, compared with the NT, in the T-cell subsets, increased percentages of effector memory T-cells and decreased percentages of terminally differentiated T-cells; higher proliferation of naive CD4+T cells stimulated with mitogen; larger telomere length in TCD3+, TCD3+CD8+ and TCD3+CD8+CD28- cells (the latter subset being a marker of immunosenescence), preservation of the anti-apoptotic mechanisms, indicated by increased Bcl-2 expression and decreased caspase-3 expression in in vitro resting memory and naive CD4+ T-cell and in senescent and non-senescent CD8+ T-cells; all of which denote a potentially better T-cell functioning. There was also increased anti-influenza antibody titers pre and post-vaccination, indicating a possible adjuvant role of intense exercise in vaccine responses. Finally there was a similar pattern between the two groups in in vitro secreted and in serum cytokines associated with Inflamm-aging. The results showed that the practice of regular intense physical activity has a protective effect against some parameters associated with immunosenescence

The social mole-rats have often been typecast as extreme examples of mammalian sociality. With their pronounced reproductive skew, status-related contrasts in lifespan and morphology, and the suggestion of a division of labour amongst helpers, mole-rat societies have repeatedly been likened to the structurally complex societies of some eusocial insects. However, because few studies of mole-rats have quantified individual variation in growth and behaviour across long periods of development, it has remained unclear the extent to which mole-rat societies, and the features of individuals within them, should be considered unique amongst social vertebrates. In this thesis, I examine life history variation in Damaraland mole-rats Fukomys damarensis from three perspectives- growth, behaviour, and ageing- to explore how individual developmental trajectories contribute to, and are influenced by, the structure of mole-rat societies. First, I use a large longitudinal dataset to test for the presence of behavioural specialisation in non-breeding mole-rat helpers. I find no indication of individual specialisation in cooperative activities. Instead, individual differences in helping behaviour are largely the result of age-related changes in the extent to which individuals commit to all forms of helping (Chapter 3); refuting the notion of helper castes. I then focus on the variation in growth across non-breeders, developing a novel biphasic model to accurately quantify sex differences in growth and explore the influence of social effects on growth trajectories (Chapter 4). Despite the proposition of intense intrasexual competition in mole-rat societies, there was no clear signature of sex-specific competition on helper growth trajectories. A more conspicuous form of socially-mediated growth in mole-rats is the secondary growth spurt displayed by females that have acquired the dominant breeding position, causing them to become larger and more elongated. By experimentally controlling reproduction in age-matched siblings, I show that rather than being stimulated by the removal from reproductive suppression, this adaptive morphological divergence is achieved through a lengthening of the lumbar vertebrae when breeding is commenced (Chapter 5). With contrasts in size and shape following the acquisition of the breeding role, this status-related growth pattern shares similarities with growth in naked mole-rats and other social vertebrates. Breeders also show a twofold greater lifespan than non-breeders in Fukomys mole-rats, prompting the suggestion that the transition to dominance also sets individuals onto a slower ageing trajectory. To date, there is little evidence to support a physiological basis to lifespan extension in breeders. This assertion is bolstered by the absence of longer telomeres or slower rates of telomere attrition in breeding females compared to non-breeding females residing in groups (Chapter 6), each of which might be expected if breeders age more slowly. I argue that previous studies exploring status-related ageing in captive Fukomys mole-rats have overlooked the importance of demographic processes (and associated behavioural influences) on mortality schedules. Irrespective of the proximate basis of the longer lifespan of breeders, at an interspecific level the social mole-rats are unusually long-lived for their size. A recent large-scale comparative analysis concluded that prolonged lifespan is a general characteristic of all mammalian cooperative breeders, but this conclusion is premature, as in most of the major clades containing both cooperative and non-cooperative species there is no consistent trend towards lifespan extension in cooperative species (Chapter 7). In the case of mole-rats, it seems more likely that their exceptional longevity arises principally from their subterranean habits and related reductions in extrinsic mortality. Overall, these findings demonstrate that cooperative breeding has important consequences for individual life histories, but there is no strong basis for the claim that Damaraland mole-rat societies are markedly different in form than other cooperative breeding societies.

O telômero é uma sequência repetitiva da dupla cadeia do DNA que protege as pontas dos cromossomos. Seu comprimento é mantido pela telomerase, cuja expressão ocorre em células de câncer, mas não em células somáticas. A célula apresenta um número definido de divisões antes do telômero sofrer erosão. A quebra do DNA ativa a p53, supressor tumoral que induz senescência e respostas de pontos de checagem. O desenvolvimento de inibidores de telomerase tem importância clínica para o câncer. Estudamos os efeitos dos inibidores de telomerase. Duas linhagens celulares LC-HK2 (NSCLC) e hTERT RPE-1 foram tratadas com os inibidores TMPyP4 (5µM) e Thymoquinone (10 e 40 µM) durante 72 e 120 h. TMPyP4 aumentou a porcentagem de células com dano na membrana, induziu mudança na morfologia da célula e diminuiu a expressão do mRNA da vimentina e vinculina. Thymoquinone aumentou a frequência de células senescentes, células com dano na membrana e induziu morte celular. Ambos os inibidores diminuíram a atividade da telomerase, afetando a proliferação e induzindo morte celular. / The telomere is a repetitive double-strand sequence of DNA that protects the chromosomes ends. Its length is maintained by telomerase, whose expression occurs in cancer cells, but not in somatic cells. The cell has a defined number of divisions before the telomere undergoes erosion. DNA break activates p53, tumor suppressor and induces senescence and checkpoint responses. The development of telomerase inhibitors is of clinical importance for cancer. We studied the effects of telomerase inhibitors. Two cell lines LC-HK2 (NSCLC) and hTERT RPE-1 were treated with inhibitors TMPyP4 (5 M) and Thymoquinone (10 and 40 M) for 72 and 120 h. TMPyP4 increased the percentage of cells with membrane damage, induced change in cell morphology, and decreased mRNA expression of vimentin and vinculin. Thymoquinone increased the frequency of senescent cells, cells with membrane damage and induced cell death. Both inhibitors decreased telomerase activity, affecting proliferation and inducing cell death.

La mastocytose est une maladie hétérogène, caractérisée par une accumulation de mastocytes dans l’organisme. Les enfants et les adultes ont des mutations différentes de c-Kit. Dans un premier travail, nous avons montré que seules les formes adultes sont associées à la réactivation de la télomérase, alors que les formes pédiatriques ne sont pas. Cela semble être lié aux différences de mutations de c-Kit observées entre adultes et enfants et pourrait expliquer pourquoi seules les formes pédiatriques de mastocytose régressent spontanément et non les formes adultes. Ces résultats aident à mieux comprendre la physiopathologie de la mastocytose. Dans un second travail, nous a étudié le lien entre la longueur des télomères et les troubles psychologiques des adultes atteints de mastocytose. Nous avons montré que réactions émotionnelles négatives sont corrélées au raccourcissement de la longueur des télomères des leucocytes et que l’érosion télomérique est fortement prédite par les défauts de régulation des émotions. Nous émettons l'hypothèse qu’au cours des troubles neuropsychologiques, le mastocyte pourrait être impliqué dans le raccourcissement de la longueur des télomères en périphérie. / Mastocytosis is a heterogeneous disease characterized by an accumulation of mast cells. Children and adults hold different c-Kit mutations. In a first work, we showed that only adult forms are associated with reactivation of telomerase whereas pediatric forms are not. This seems to be linked to the differential c-Kit mutations observed between adults and children and could explain why only pediatric mastocytosis spontaneously regress in comparison with adult forms. These results help to better elucidate the pathophysiology of mastocytosis. In a second work, we studied the link between the telomere length and the psychological features of adults with mastocytosis and showed that negative emotionality correlated negatively to telomere length and that telomere shortening was strongly predicted by emotion regulation deficits. We hypothesize that in psychological disorders, mast cell may represent the link between brain and periphery and induce telomere shortening.