Genetic Basis of Thermal Divergence in Saccharomyces Species

Genetic Basis of Thermal Divergence in Saccharomyces Species PDF Author: Xueying C. Li
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 186

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Book Description
The genetic architecture of phenotypic divergence is a central question in evolutionary biology. Genetic architecture is impacted by whether evolution occurs through accumulation of many small-effect or a few large-effect changes, the relative contribution of coding and cis-regulatory changes, and the prevalence of epistatic effects. Our empirical understanding of the genetic basis of evolutionary change remains incomplete, largely because reproductive barriers limit genetic analysis to those phenotypes that distinguish closely related species. In this dissertation, I use hybrid genetic analysis to examine the basis of thermal divergence between two post-zygotically isolated species, Saccharomyces cerevisiae and S. uvarum. S. cerevisiae is relatively heat tolerant, whereas S. uvarum is heat sensitive but outperforms S. cerevisiae at 4°C. Gene expression analysis with an S. cerevisiae and S. uvarum hybrid revealed a small set of 136 genes with temperature-dependent cis-acting differences, suggesting that the temperature divergence has not caused widespread cis-regulatory divergence. Using a genome-wide non-complementation screen, I found a single nuclear-encoded gene with a modest contribution to heat tolerance, and a large effect of the species' mitochondrial DNA (mitotype). Recombinant mitotypes and allele replacements indicate multiple mitochondria-encoded genes contribute to thermal divergence, with the coding sequence of COX1 showing a moderate effect on both heat and cold tolerance. The non-complementation approach also identified allele differences of CUP2, a copper-binding transcription factor, in copper resistance of S. cerevisiae and S. uvarum. Chimeric alleles showed that multiple changes underlie the resistance of S. cerevisiae CUP2, with cis-regulatory changes having a larger effect than coding changes. Taken together, my findings suggest that evolution of interspecific phenotypic differences often involves accumulation of small-to-medium effect changes, such as those in mitochondrial DNA and CUP2, and can occur through both coding and cis-regulatory changes.

Genetic Basis of Thermal Divergence in Saccharomyces Species

Genetic Basis of Thermal Divergence in Saccharomyces Species PDF Author: Xueying C. Li
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 186

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Book Description
The genetic architecture of phenotypic divergence is a central question in evolutionary biology. Genetic architecture is impacted by whether evolution occurs through accumulation of many small-effect or a few large-effect changes, the relative contribution of coding and cis-regulatory changes, and the prevalence of epistatic effects. Our empirical understanding of the genetic basis of evolutionary change remains incomplete, largely because reproductive barriers limit genetic analysis to those phenotypes that distinguish closely related species. In this dissertation, I use hybrid genetic analysis to examine the basis of thermal divergence between two post-zygotically isolated species, Saccharomyces cerevisiae and S. uvarum. S. cerevisiae is relatively heat tolerant, whereas S. uvarum is heat sensitive but outperforms S. cerevisiae at 4°C. Gene expression analysis with an S. cerevisiae and S. uvarum hybrid revealed a small set of 136 genes with temperature-dependent cis-acting differences, suggesting that the temperature divergence has not caused widespread cis-regulatory divergence. Using a genome-wide non-complementation screen, I found a single nuclear-encoded gene with a modest contribution to heat tolerance, and a large effect of the species' mitochondrial DNA (mitotype). Recombinant mitotypes and allele replacements indicate multiple mitochondria-encoded genes contribute to thermal divergence, with the coding sequence of COX1 showing a moderate effect on both heat and cold tolerance. The non-complementation approach also identified allele differences of CUP2, a copper-binding transcription factor, in copper resistance of S. cerevisiae and S. uvarum. Chimeric alleles showed that multiple changes underlie the resistance of S. cerevisiae CUP2, with cis-regulatory changes having a larger effect than coding changes. Taken together, my findings suggest that evolution of interspecific phenotypic differences often involves accumulation of small-to-medium effect changes, such as those in mitochondrial DNA and CUP2, and can occur through both coding and cis-regulatory changes.

Functional and Comparative Genomics of Saccharomyces and non-Saccharomyces Yeasts: Potential for Industrial and Food Biotechnology

Functional and Comparative Genomics of Saccharomyces and non-Saccharomyces Yeasts: Potential for Industrial and Food Biotechnology PDF Author: Isabel Sá-Correia
Publisher: Frontiers Media SA
ISBN: 2889635228
Category :
Languages : en
Pages : 255

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Book Description
Since 1996, when the first Saccharomyces cerevisiae genome sequence was released, a wealth of genomic data has been made available for numerous S. cerevisiae strains, its close relatives, and non-conventional yeast species isolates of diverse origins. Several annotated genomes of interspecific hybrids, both within the Saccharomyces clade and outside, are now also available. This genomic information, together with functional genomics and genome engineering tools, is providing a holistic assessment of the complex cellular responses to environmental challenges, elucidating the processes underlying evolution, speciation, hybridization, domestication, and uncovering crucial aspects of yeasts´ physiological genomics to guide their biotechnological exploitation. S. cerevisiae has been used for millennia in the production of food and beverages and research over the last century and a half has generated a great deal of knowledge of this species. Despite all this, S. cerevisiae is not the best for all uses and many non-conventional yeast species have highly desirable traits that S. cerevisiae does not have. These include tolerance to different stresses (e.g. acetic acid tolerance in Zygosaccharomyces bailii, osmotolerance in Z. rouxii, and thermotolerance in Kluyveromyces marxianus and Ogataea (Hansenula) polymorpha), the capacity of assimilation of diverse carbon sources (e.g. high native capacity to metabolyze xylose and potential for the valorization of agroforest residues by Scheffersomyces (Pichia) stipites), as well as, high protein secretion, fermentation efficiency and production of desirable flavors, capacity to favor respiration over fermentation, high lipid biosynthesis and accumulation, and efficient production of chemicals other than ethanol amongst many. Several non-Saccharomyces species have already been developed as eukaryotic hosts and cell factories. Others are highly relevant as food spoilers or for desirable flavor producers. Therefore, non-conventional yeasts are now attracting increasing attention with their diversity and complexity being tackled by basic research for biotechnological applications. The interest in the exploitation of non-conventional yeasts is very high and a number of tools, such as cloning vectors, promoters, terminators, and efficient genome editing tools, have been developed to facilitate their genetic engineering. Functional and Comparative Genomics of non-conventional yeasts is elucidating the evolution of genome functions and metabolic and ecological diversity, relating their physiology to genomic features and opening the door to the application of metabolic engineering and synthetic biology to yeasts of biotechnological potential. We are entering the era of the non-conventional yeasts, increasing the exploitation of yeast biodiversity and metabolic capabilities in science and industry. In this collection the industrial properties of S. cerevisiae, in particular uses, are explored along with its closely related species and interspecific hybrids. This is followed by comparisons between S. cerevisiae and non-conventional yeasts in specific applications and then the properties of various non-conventional yeasts and their hybrids.

Ecological Communities

Ecological Communities PDF Author: Donald R. Strong Jr.
Publisher: Princeton University Press
ISBN: 1400857082
Category : Science
Languages : en
Pages : 629

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Book Description
This work is the first to focus systematically on a much-debated topic: the conceptual issues of community ecology, including the nature of evidence in ecology, the role of experiments, attempts to disprove hypotheses, and the value of negative evidence in the discipline. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

The Genetic Bases of Ecological Specialization and the Effects of Hybridization in a Complex of Incipient Yeast Species

The Genetic Bases of Ecological Specialization and the Effects of Hybridization in a Complex of Incipient Yeast Species PDF Author: Chris Eberlein
Publisher:
ISBN:
Category :
Languages : en
Pages : 188

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Book Description
Millions of different species inhabiting the world have evolved through complex interactions with their environment. Contemporary evolutionary biology is experiencing a revolution in genome sequencing, screening and genetic manipulation technologies. Its aim, however, remains the same as 160 years ago when pioneers like Darwin and Wallace published the first articles about the evolutionary theory: to understand the underlying mechanisms involved in speciation, because such knowledge is key to shed light into species diversification. This can be achieved by studying the genetic mechanisms involved in local adaptation and ecological specialization during early speciation events. The main objective of this work is to investigate the molecular mechanisms underlying adaptation and population differentiation in a young species complex of the budding yeast Saccharomyces paradoxus, naturally found in the North American deciduous forests. Using different approaches, such as population genomics, experimental biology, transcriptomics and high-throughput phenotyping we (1) dissect the genetic bases for ecological specialization and (2) investigate the effect of hybridization in facilitating rapid divergence and speciation. First, we document that the ecological specialization to different temperatures, a phenotype that has been previously shown to play an important role in the divergence of two main S. paradoxus lineages, is partially driven by relaxed selection with trade-offs. Second, with the work on two inter-species hybridization events, we document a back-cross between a hybrid taxa and its parental species, which highlights that hybridization is likely more common in the evolution of species than previously thought. Our work underlines the importance of ecological differentiation through relaxed selection, rather than adaptive divergence from the fixation of beneficial mutations. Additionally, our findings show that hybridization in nature likely plays an important role in creating new diversity through transgressive segregation, and that this can reiterate through crosses that include hybrid species. Studies on young species and hybrid complexes will enable to further understand the genetic bases of population differentiation and the consequences of inter-species hybridization and its recurrence in the origin of species.

Dissecting the Genetic Basis of Reproductive Isolation Between Two Closely Related Saccharomyces Species

Dissecting the Genetic Basis of Reproductive Isolation Between Two Closely Related Saccharomyces Species PDF Author: Wesley T. Loo
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Yeasts in Natural Ecosystems: Ecology

Yeasts in Natural Ecosystems: Ecology PDF Author: Pietro Buzzini
Publisher: Springer
ISBN: 3319615750
Category : Science
Languages : en
Pages : 299

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Book Description
This book presents an up-to-date review of the ecology of yeast communities in natural ecosystems. It focuses on their biological interactions, including mutualism, parasitism, commensalism and antagonistic interactions, and is closely connected with the volume Yeasts in Natural Ecosystems: Diversity by the same editors. Yeasts are the smallest eukaryotic organisms successfully growing under a wide range of environmental conditions. They constantly modify the environment through their own metabolic activities. Although yeasts are among the earlier colonizers of nutrient-rich substrates, their role in ecosystem processes is not limited to the consumption and transformation of simple sugars. They also engage in close relationships with animals, plants and other fungi in the environment as mutualists, competitors, parasites and pathogens. This book reviews the diversity of biological interactions and roles of yeasts in ecosystems and summarises recent concepts and tools developed in community ecology. All of the chapters were written by leading international yeast research experts, and will appeal to researchers and advanced students in the field of microbial ecology.

The Yeasts

The Yeasts PDF Author: Cletus Kurtzman
Publisher: Elsevier
ISBN: 0080931278
Category : Science
Languages : en
Pages : 2362

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Book Description
The Yeasts: A Taxonomic Study is a three-volume book that covers the taxonomic aspect of yeasts. The main goal of this book is to provide important information about the identification of yeasts. It also discusses the growth tests that can be used to identify different species of yeasts, and it examines how the more important species of yeasts provide information for the selection of species needed for biotechnology. • Volume 1 discusses the identification, classification and importance of yeasts in the field of biotechnology. • Volume 2 focuses on the identification and classification of ascomycetous yeasts. • Volume 3 deals with the identification and classification of basidiomycetous yeasts, along with the genus Prototheca. - High-quality photomicrographs and line drawings - Detailed phylogenetic trees - Up-to-date, clearly presented yeast taxonomy and systematic, easy-to-use reference sequence accession numbers to allow for correct identification

Research Awards Index

Research Awards Index PDF Author:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 742

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Book Description


International Review of Cytology

International Review of Cytology PDF Author:
Publisher: Academic Press
ISBN: 0080586309
Category : Science
Languages : en
Pages : 383

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Book Description
International Review of Cytology

Evolutionary Genetics and Dissection of Brewing Related Traits in Saccharomyces Eubayanus and Its Hybrids with Saccharomyces Cerevisiae

Evolutionary Genetics and Dissection of Brewing Related Traits in Saccharomyces Eubayanus and Its Hybrids with Saccharomyces Cerevisiae PDF Author: EmilyClare Patricia Baker
Publisher:
ISBN:
Category :
Languages : en
Pages : 172

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Book Description
Successful colonization of new environments requires that organisms evolve to cope with conditions they could not previously tolerate and to exploit resources they could not previously utilize. These changes in selective pressures leave an imprint on organisms from the level of the gene to the whole genome. Over time, some strains of Saccharomyces yeasts have successfully evolved to thrive in industrial fermentations. Here, they regularly contend with conditions and experience population sizes they would have rarely encountered in wild settings. Understanding the genetic basis for their success can provide greater insight into the molecular basis of adaptation across the tree of life. Because many of the strains of Saccharomyces found in fermentative environments are hybrids between distantly related species this system also provides the opportunity to explore not only how interactions between an organism and its external environment have shaped its genome, but also how interactions between two diverged genomes when brought together in single nucleus shape each other. The work reported in this thesis explores evolutionary genetics in the yeast Saccharomyces eubayanus and its hybrids with Saccharomyces cerevisiae. Taking advantage of the deep foundation of tools and knowledge from S. cerevisiae research, evolution and adaptation of S. eubayanus and its hybrids is explored at scales ranging from the whole genome to a single genetic locus and across a range of conditions. This work provides a deeper understanding of the mechanisms of adaptation and demonstrates the potential of S. eubayanus and its hybrids as a system for future genetic studies.