The Evolving Telomeres
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The Evolving Telomeres
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Author : Arthur J. Lustig
language : en
Publisher: Frontiers Media SA
Release Date : 2016-07-19
The Evolving Telomeres written by Arthur J. Lustig and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-07-19 with Genetics categories.
What controls the different rates of evolution to give rise to conserved and divergent proteins and RNAs? How many trials until evolution can adapt to physiological changes? Every organism has arisen through multiple molecular changes, and the mechanisms that are employed (mutagenesis, recombination, transposition) have been an issue left to the elegant discipline of evolutionary biology. But behind the theory are realities that we have yet to ascertain: How does an evolving cell accommodate its requirements for both conserving its essential functions, while also providing a selective advantage? In this volume, we focus on the evolution of the eukaryotic telomere, the ribo-nuclear protein complex at the end of a linear chromosome. The telomere is an example of a single chromosomal element that must function to maintain genomic stability. The telomeres of all species must provide a means to avoid the attrition from semi-conservative DNA replication and a means of telomere elongation (the telomere replication problem). For example, telomerase is the most well-studied mechanism to circumvent telomere attrition by adding the short repeats that constitutes most telomeres. The telomere must also guard against the multiple activities that can act on an unprotected double strand break requiring a window (or checkpoint) to compensate for telomere sequence loss as well as protection against non-specific processes (the telomere protection problem). This volume describes a range of methodologies including mechanistic studies, phylogenetic comparisons and data-based theoretical approaches to study telomere evolution over a broad spectrum of organisms that includes plants, animals and fungi. In telomeres that are elongated by telomerases, different components have widely different rates of evolution. Telomerases evolved from roots in archaebacteria including splicing factors and LTR-transposition. At the conserved level, the telomere is a rebel among double strand breaks (DSBs) and has altered the function of the highly conserved proteins of the ATM pathway into an elegant means of protecting the chromosome end and maintaining telomere size homeostasis through a competition of positive and negative factors. This homeostasis, coupled with highly conserved capping proteins, is sufficient for protection. However, far more proteins are present at the telomere to provide additional species-specific functions. Do these proteins provide insight into how the cell allows for rapid change without self-destruction?
The Evolving Telomeres
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Author :
language : en
Publisher:
Release Date : 2016
The Evolving Telomeres written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
What controls the different rates of evolution to give rise to conserved and divergent proteins and RNAs? How many trials until evolution can adapt to physiological changes? Every organism has arisen through multiple molecular changes, and the mechanisms that are employed (mutagenesis, recombination, transposition) have been an issue left to the elegant discipline of evolutionary biology. But behind the theory are realities that we have yet to ascertain: How does an evolving cell accommodate its requirements for both conserving its essential functions, while also providing a selective advantage? In this volume, we focus on the evolution of the eukaryotic telomere, the ribo-nuclear protein complex at the end of a linear chromosome. The telomere is an example of a single chromosomal element that must function to maintain genomic stability. The telomeres of all species must provide a means to avoid the attrition from semi-conservative DNA replication and a means of telomere elongation (the telomere replication problem). For example, telomerase is the most well-studied mechanism to circumvent telomere attrition by adding the short repeats that constitutes most telomeres. The telomere must also guard against the multiple activities that can act on an unprotected double strand break requiring a window (or checkpoint) to compensate for telomere sequence loss as well as protection against non-specific processes (the telomere protection problem). This volume describes a range of methodologies including mechanistic studies, phylogenetic comparisons and data-based theoretical approaches to study telomere evolution over a broad spectrum of organisms that includes plants, animals and fungi. In telomeres that are elongated by telomerases, different components have widely different rates of evolution. Telomerases evolved from roots in archaebacteria including splicing factors and LTR-transposition. At the conserved level, the telomere is a rebel among double strand breaks (DSBs) and has altered the function of the highly conserved proteins of the ATM pathway into an elegant means of protecting the chromosome end and maintaining telomere size homeostasis through a competition of positive and negative factors. This homeostasis, coupled with highly conserved capping proteins, is sufficient for protection. However, far more proteins are present at the telomere to provide additional species-specific functions. Do these proteins provide insight into how the cell allows for rapid change without self-destruction?
Origin And Evolution Of Telomeres
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Author : Jozef Nosek
language : en
Publisher: CRC Press
Release Date : 2008-05-26
Origin And Evolution Of Telomeres written by Jozef Nosek and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-05-26 with Science categories.
Linear chromosomes represent an evolutionary innovation associated with the origin of eukaryotic cells. This book describes how linear chromosomes and primordial pathways for maintaining their terminal structures, telomeres, emerged in early eukaryotes.Telomeres, derived from the Greek meaning terminal part, were first described by Hermann Muller i
Origin And Evolution Of Telomeres
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Author : Jozef Nosek
language : en
Publisher:
Release Date : 2008-07
Origin And Evolution Of Telomeres written by Jozef Nosek and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-07 with categories.
The Role Of Telomeres In The Evolution Of Exceptional Longevity In Bats
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Author : Nicole M. Foley
language : en
Publisher:
Release Date : 2017
The Role Of Telomeres In The Evolution Of Exceptional Longevity In Bats written by Nicole M. Foley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Bats categories.
The Evolution Of Avian Lifespan
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Author : Mark Frederick Haussmann
language : en
Publisher:
Release Date : 2005
The Evolution Of Avian Lifespan written by Mark Frederick Haussmann and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Identifying and understanding the processes that underlie variation in lifespan within and among species is a central area of biological research. Questions centered on how and why organisms grow old link disciplines such as evolutionary ecology to cell biology and gerontology. One process now known to be pivotal in this area is the erosion of the protective ends of chromosomes, the telomeres, which occurs during cell replication. Telomeres play a central role in cellular senescence, but we currently know very little about how telomere dynamics affect organism aging on the whole, as well as variation in maximum lifespan between species. In this context, this dissertation intends to explore telomere dynamics association with aging patterns, lifespan and survival in birds, which are an interesting taxonomic group to explore patterns of senescence. As a group, birds tend to be longer lived than mammals of similar size, despite factors such as high metabolic rates that should accelerate aging. The long lifespan of many birds suggest they have evolved physiological mechanisms to protect against aging. In this dissertation, I begin by reviewing what we currently know about telomeres, aging and lifespan and describe an interesting link between telomeres and lifestyle. I then explain how knowledge of telomere length can be used to estimate ages of free-living birds. Next, I investigate the rate at which telomeres shorten in avian species which vary broadly in their maximum lifespan and describe a fundamental link between the rate at which telomeres shorten and the maximum lifespan a species can attain. I also show that telomerase, an enzyme capable of elongating telomeres may be responsible for this relationship. Within populations, I describe how telomere length may be associated with individual survival and that telomere length is heritable. Near the end of the dissertation, I depart from the telomere dynamics studies and describe immunosenescence of cell-mediated immunity in three avian species. My dissertation work centers on age-old questions in biology concerning how and why organisms grow old. Taken together, these studies demonstrate that telomere dynamics play an important role in the evolution of avian aging, survival and lifespan.
Patterns Of Telomere Length Change With Age In Aquatic Vertebrates And The Phylogenetic Distribution Of The Pattern Among Jawed Vertebrates
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Author : Christopher Izzo
language : en
Publisher:
Release Date : 2010
Patterns Of Telomere Length Change With Age In Aquatic Vertebrates And The Phylogenetic Distribution Of The Pattern Among Jawed Vertebrates written by Christopher Izzo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Aquatic animals categories.
Telomeres, the protective caps at the ends of all vertebrate chromosomes, naturally undergo changes in length. These changes in telomere lengths may be a "molecular clock" by providing a counting mechanism of DNA replication events. In populations of jawed vertebrates (gnathostomes), telomere length has been shown to change with age; and thus measurements of telomere lengths may provide a novel means of determining the ages of free-living animals. Determinations of the age structure of populations of aquatic vertebrates (teleosts, chondrichthyans and marine mammals) are vital for sustainable management and conservation efforts. Yet, the commonly applied increment based ageing techniques are limited by the subjectivity of increment patterning and destructive sampling. I aimed to assess the application of telomere length as an age determinate for populations of aquatic vertebrates and to evaluate the biological implications and evolutionary origins of this trait amongst the gnathostomes. Telomere length change with age was investigated in an exemplar chondrichthyan, teleost and marine mammal species, to determine whether aquatic gnathostomes share the general pattern of declining telomeres with age, as found in terrestrial mammals. Chapter Two provides the first assessment of telomere length change with age in a chondrichthyan species, the Port Jackson shark. Four types of tissues from Port Jackson sharks, ranging in age from 0 to 17 years, were sampled and telomere length were estimated using three measurement methods: (i) relative quantitative PCR (qPCR); (ii) absolute qPCR; and (iii) the terminal restriction fragment (TRF) analysis. No relationship between telomere length and age was found for any of the tissues, using any method. In Chapter Three, telomere length was measured in specimens of the common carp from two tissues using the absolute qPCR method. Telomere length measurements were then correlated with ages estimated from otolith increment counts and length-at-age calculations. Measurements of telomere length were highly variable in both muscle biopsies and fin clips; however, telomeres from muscle biopsies significantly increased in length - in contrast to the more generalised pattern of telomere length attrition and marking the second reported case of an increase in telomere length with age in vertebrates. In terrestrial mammals telomere shortening is negatively correlated with donor age. In Chapter Four, I tested whether this pattern of declining telomere lengths was found in a pinniped species, the Australian sea lion. Telomere lengths were measured in flipper clips from specimens by absolute qPCR and compared between three age classes: pups, juveniles, and adults. Mean telomere lengths of the adults were significantly smaller than the juvenile and pup classes confirming that the Australian sea lion shares the general mammalian pattern of telomere length attrition. Relationships between the rate of telomere length change with age and species longevity have been observed in birds and mammals, suggesting that the rate of telomere length change is an informative measure of ageing. In Chapter Five, using a data set of 20 teleost and chondrichthyan species, I tested whether fishes showed a similar pattern. I found that the rate of telomere length change with age is significantly different between species of fishes and that these rates of change are inversely correlated with longevity. The findings of Chapters Two, Three & Four indicated that telomeres do not provide a suitable means of determining the ages of individuals and at best are limited to assigning broad age classes. This is largely due to the high degree of variability of telomere lengths between individuals within all age classes. In addition, these Chapters (2, 3 & 4) also highlight that patterns of telomere length change with age are highly variable within the gnathostomes; and thus, telomere length change cannot be characterised by a single pattern for all lineages. In fact, three patterns of telomere length change with age in the gnathostomes were found: (i) declining telomere lengths; (ii) increasing telomere lengths; and (iii) no significant change in telomere length with age. However, identifying the selective factors responsible for the assignment of patterns of telomere length change is hampered by a lack of the understanding of the evolutionary origins of these patterns. Therefore, in Chapter Six I sought to outline the phylogenetic distribution of patterns of telomere length change with age in the gnathostomes to determine the evolutionary origin(s) of this trait. Two alternative hypotheses for the evolution of telomere length change were tested by ancestral state reconstruction in a set of 40 gnathostomes, for which I have significantly expanded the sampling of chondrichthyans and teleosts. The most likely/parsimonious pattern of telomere length change in the common gnathostome ancestor suggested that telomere length change with age was not present ancestrally and has since evolved independently. I was also able to elucidate the evolutionary history of transitions to and between the three patterns of telomere length change within the available gnathostome lineages, with the birds and teleosts displaying the highest rates of evolutionary lability of patterns of telomere length change with age. The macro-evolutionary analysis (Chapter 6) identified relatively rapid evolutionary patterns of telomere length change with age in two gnathostome clades. However, as highlighted by the variability of telomere lengths among individuals within all age classes, furthering an interpretation of the causes and consequences of variable patterns of telomere length change will require a focus at the species level and a shift to following individuals through out their lifetime.
Telomeres In Ecology And Evolution
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Author : David Gómez Blanco
language : en
Publisher:
Release Date : 2023
Telomeres In Ecology And Evolution written by David Gómez Blanco and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Studying life history strategies is crucial for understanding the diversity among organisms. The trade-offs in traits related to survival, self-maintenance and reproduction play an important role in the variation of life histories and can be adjusted in response to environmental and physiological factors. Telomeres, which are repetitive DNA sequences found at the ends of chromosomes, can serve as molecular markers linking these factors and ultimately fitness. Telomeres naturally shorten with age and stress, such as diseases, and when they become too short, they trigger cellular senescence and ageing. However, some telomere restoration mechanisms can counteract this process. In this thesis, first I have adopted a theoretical approach to review the telomere research field and develop hypotheses for future exploration. Then, I also included an empirical section that aimed to evaluate and test some of these hypotheses' general patterns using data from a wild population of the polygynous bird species, the great reed warbler (Acrocephalus arundinaceus). I have taken advantage of the longitudinal study conducted for 40 years at Lake Kvismaren that have collected a comprehensive dataset on life history, behaviours and fitness components, along with a sampling of all the bird born and breeding in the area. I measured telomere length using the quantitative PCR method, and to investigate the ecological and evolutionary implications of parasites, I used the multiplex PCR method to detect the presence of avian malaria parasites in the birds' blood. In the first part of this thesis, I and my collaborators present a summary of telomere hypotheses that apply to the fields of ecology and evolution. We also classify and group these hypotheses based on their research context and hierarchical similarities. Furthermore, we identify gaps in the knowledge, such as the lack of hypotheses that can clarify telomere elongation patterns in the wild. As a result, we propose and expand on a novel hypothesis that highlights the significance of elongation patterns and encourages further exploration in this area of telomere dynamics. The second section of the thesis aimed to test some of the assumptions made in the previous hypotheses. The studies were focused on examining the existence of a lower threshold for telomere length and I revealed that individuals with critically short telomeres disappeared from the population at a greater rate than those with longer telomeres. Furthermore, life stressors such as infections had an impact on these selection patterns. In this thesis, I also found that even in early-life a considerable percentage of individuals can display a net increase in telomere length (telomere elongation), and this prospect was dependent on factors like infection and the current telomere length. Finally, this thesis demonstrates that various factors including age, malaria status, and harem size can predict the dynamics of telomere length in male and female great reed warblers. These sex-specific telomere dynamics could potentially provide indications of the individual's phenotypic quality. In summary, this thesis has contributed to our understanding of telomere dynamics in the wild, particularly concerning the complex interactions between telomere length, infections and life history trade-offs. It has addressed some gaps in our knowledge of telomere biology and provided insights into important yet under-explored areas, like telomere elongation patterns. The thesis highlights the need for further research into telomere elongation events, the impact of short telomeres on individual life histories, and the potential use of telomeres as a biomarker for individual quality or as a measure of environmental stressors faced.
Telomerases
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Author : Neal F. Lue
language : en
Publisher: John Wiley & Sons
Release Date : 2012-05-22
Telomerases written by Neal F. Lue and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-05-22 with Science categories.
This book is a comprehensive and up-to-date review and evaluation of the contemporary status of telomerase research. Chapters in this volume cover the basic structure, mechanisms, and diversity of the essential and regulatory subunits of telomerase. Other topics include telomerase biogenesis, transcriptional and post-translational regulation, off-telomere functions of telomerase and the role of telomerase in cellular senescence, aging and cancer. Its relationship to retrotransposons, a class of mobile genetic elements that shares similarities with telomerase and serves as telomeres in selected organisms, are also reviewed.
Telomeres And Telomerase In Cancer
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Author : Keiko Hiyama
language : en
Publisher: Springer Science & Business Media
Release Date : 2009-03-18
Telomeres And Telomerase In Cancer written by Keiko Hiyama and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-03-18 with Medical categories.
Telomerase, an enzyme that maintains telomeres and endows eukaryotic cells with immortality, was first discovered in tetrahymena in 1985. In 1990s, it was proven that this enzyme also plays a key role in the infinite proliferation of human cancer cells. Now telomere and telomerase are widely accepted as important factors involved in cancer biology, and as promising diagnostic tools and therapeutic targets. Recently, role of telomerase in “cancer stem cells” has become another attractive story. Until now, there are several good books on telomere and telomerase focusing on biology in ciliates, yeasts, and mouse or basic sciences in human, providing basic scientists or students with updated knowledge.
