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This book presents a universal picture of the impact of climate change on food production, diversity, and concerns regarding food safety. The book also highlights the traditional and modern techniques for sustainably improving the production of food crops and their nutritional quality aligning with the “zero hunger” goal (Sustainable Development Goal 2) of the United Nations. The book holistically includes the contributions of scientists and academicians working in the fields of Food and Nutrition, Plant and Microbial Sciences, Agriculture, etc. The book also offers insights into the strategies adopted worldwide for ensuring food availability and safety, taking the aid of advanced technologies like climate-smart agriculture along with nanotechnology and artificial intelligence in the event of climate change. Above all, the book transpires the subject matter using illustrative figures and outlines and therefore will be an asset for the post-graduate students, researchers, and faculties.

This book focuses primarily on evolutionary processes (rather than evolutionary history). Topics covered are abiotic framework conditions, morphology and physiology of living organisms, fossil and molecular evidence of evolutionary developments. The basic processes of biological evolution are already established in unicellular organisms. Evolutionary options for multicellular organisms arise in a simplified way from the usable energetic transformation potentials and the dynamics of abiotic and biotic interactions. Evolutionary processes of multicellular organisms are therefore predominantly determined by the conditions of the surrounding systems. This is most clearly shown by comparisons of the evolutionary development of vertebrates under marine and terrestrial conditions. For reasons of efficiency alone, no single species can have the equipment to capture and sustainably shape the surrounding systems in the long term. Depending on the available energetic transformation potentials, a single species is very well able to change the surrounding systems - but without being able to capture the resulting long-term consequences. This gives rise to fundamentally new questions for the design and limits of social action that makes sense in the long term. This book is a translation of an updated and revised version of the original German work: Relativität der Evolution, ISBN 978-3-662-63936-8. Translated by Robert D. Martin.

This volume provides in depth reviews of the protein targeting translocation processes, gene transfer processes and genome reduction processes in the host and in the endosymbiont which were likely utilized during the evolution of an endosymbiont into mitochondria, mitochondria related organelles, simple and complex chloroplasts. These reviews cover both the current understanding of the host processes as well as the evolutionary outcomes used by these organelles for protein targeting and translocation. Reviews of the current knowledge of these topics are plentiful but scattered throughout the bacterial, parasite, plant and animal literature; here, reviews of current knowledge with evolutionary outcomes and future perspectives, written by leading researchers in their respective areas, are united into one comprehensive volume, essential for students and scientists interested in or working onsubcellular protein localization, protein targeting signals, translocation of proteins across and insertion into membranes, nucleic acid transfer between genomes, genome reduction and evolution of mitochondria and chloroplast.

Sequence analyses of numerous fungal genomes over the past two decades have provided us with extensive insights into the phylogenetic relationships of fungi and the distribution of genes and their inferred functions, across the fungal kingdom. It is now possible to answer questions about the origin of the fungal kingdom and fungal evolution with an analytical precision that was not possible before.This fully revised and updated 2nd edition of The Mycota, Vol. 14, addresses major aspects of fungal evolution. The book is divided into four sections covering the following main topics:•Evolutionary roots of fungi•Evolution of pathogenic strategies•Evolution of mutualistic interactions•Evolution of metabolism and development in fungiFungi are among the oldest eukaryotic groups in the living world. The aim of this book is to better understand the history and importance of fungi, as well as the characteristics that distinguish them from their sister group, the metazoans, and other fungus-like groups such as the slime molds and oomycetes. Many fungal species are important pathogens of animals and plants and have distinct but parallel pathogenicity strategies. Mutualistic interactions of fungi with other organisms are crucial for their survival in different ecological niches and have a great influence on their evolution and the design of their genomes. Metabolism is one of the most important features of life, and the diversity of metabolic processes is best understood by considering evolution. Studies of fungal metabolism have traditionally focused on metabolites of particular interest, namely mycotoxins, pathogenicity factors, antibiotics, and other compounds with interspecific activity. This volume will be of great interest to mycologists, evolutionary biologists, and fungal geneticists, as well as to lecturers and students of microbiology and mycology.

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences. This latest volume includes reviews on plant physiology, biochemistry, genetics and genomics, forests, and ecosystems.

Dieses Werk fokussiert vor allem auf evolutionäre Prozesse (und weniger auf evolutionäre Geschichte). Themen sind abiotische Rahmenbedingungen, Morphologie und Physiologie lebender Organismen, fossile und molekulare Hinweise auf evolutionäre Entwicklungen. Die grundlegenden Prozesse biologischer Evolution sind bereits in einzelligen Organismen festgelegt. Entwicklungsoptionen für vielzellige Organismen ergeben sich vereinfacht durch die nutzbaren energetischen Umwandlungspotenziale und die Dynamik der abiotischen und biotischen Wechselwirkungen. Evolutionsprozesse vielzelliger Organismen sind deshalb überwiegend durch die Bedingungen der umgebenden Systeme bedingt. Am deutlichsten zeigen dies Vergleiche der evolutionären Entwicklung von Wirbeltieren unter marinen und terrestrischen Bedingungen.Allein aus Effizienzgründen kann keine einzige Art die Ausstattung für die Erfassung und langfristig nachhaltige Gestaltung der umgebenden Systeme besitzen. Abhängig von den verfügbaren energetischen Umwandlungspotenzialen ist eine einzelne Art sehr wohl in der Lage die umgebenden Systeme zu verändern – allerdings ohne die daraus resultierenden langfristigen Folgewirkungen erfassen zu können. Daraus ergeben sich grundsätzlich neue Fragestellungen für die Gestaltung und Grenzen eines langfristig sinnvollen gesellschaftlichen Handelns.

This volume presents the current status of software development in the field of computational and theoretical chemistry and gives an overview of the emerging trends. The challenges of maintaining the legacy codes and their adaptation to the rapidly growing hardware capabilities and the new programming environments are surveyed in a series of topical reviews written by the core developers and maintainers of the popular quantum chemistry and molecular dynamics programs. Special emphasis is given to new computational methodologies and practical aspects of their implementation and application in the computational chemistry codes. Modularity of the computational chemistry software is an emerging concept that enables to bypass the development and maintenance bottleneck of the legacy software and to customize the software using the best available computational procedures implemented in the form of self-contained modules. Perspectives on modular design of the computer programs for modeling molecular electronic structure, non-adiabatic dynamics, kinetics, as well as for data visualization are presented by the researchers actively working in the field of software development and application. This volume is of interest to quantum and computational chemists as well as experimental chemists actively using and developing computational software for their research.Chapters'MLatom 2: An Integrative Platform for Atomistic Machine Learning” and “Evolution of the Automatic Rhodopsin Modeling (ARM) Protocol'are available open access under a CC BY 4.0 License via link.springer.com.

This book explains the metabolic processes by which microbes obtain and control the intracellular availability of their required metal and metalloid ions. The book also describes how intracellular concentrations of unwanted metal and metalloid ions successfully are limited. Its authors additionally provide information about the ways that microbes derive metabolic energy by changing the charge states of metal and metalloid ions.Part one of this book provides an introduction to microbes, metals and metalloids. It also helps our readers to understand the chemical constraints for transition metal cation allocation.Part two explains the basic processes which microbes use for metal transport. That section also explains the uses, as well as the challenges, associated with metal-based antimicrobials.Part three gives our readers an understanding that because of microbial capabilities to process metals and metalloids, the microbes have become our best tools for accomplishing many jobs. Their applications in chemical technology include the design of microbial consortia for use in bioleaching processes that recover metal and metalloid ions from industrial wastes. Many biological engineering tasks, including the synthesis of metal nanoparticles and similar metalloid structures, also are ideally suited for the microbes. Part four describes unique attributes associated with the microbiology of these elements, progressing through the alphabet from antimony and arsenic to zinc.

Diatoms are the most species rich group of algae, and they contribute about 20% of annual global carbon fixation. They play major roles in ocean food webs and global biogeochemical cycles. They are also a target of the biotechnology industry because of their nano-patterned silica cell wall and high lipid content. Diatoms have received increasing attention as more genomes became available and because of the development of genome editing tools such as the CRISPR/Cas9 technology, which has made diatoms as genetically tractable as well-established biological model species. This book provides an overview on diatom molecular biology. It brings together international leading experts in the field to discuss the latest data and developments from genes to ecosystems. As the understanding of diatoms is currently experiencing a step change, it is critical to allow for synergistic approaches on diverse aspects of diatom biology and evolution. The books offers fundamental insights into the molecular life of diatoms; at the same time new scientific concepts are developed based on the application of the latest molecular tools and genomic information to explore the fascinating lifestyle of diatoms.

This book explains how microorganisms play a pivotal role in the formation of biominerals, including carbonates, silicate minerals and oxides. As readers will learn, these minerals may be produced either intracellularly or extracellularly in order to sustain microbial life. Experienced scientists from the field show that some of these biominerals can be produced in an active form, which involves direct enzymatic intervention to form precipitates. In addition, passive mineral formation can be mediated by the presence of dead cells. Readers from Microbiology and Biochemistry will appreciate the thorough coverage on various types of microbial mineral formation and their roles in microbial domains. Furthermore, they will benefit from the authors'first-hand knowledge regarding common techniques for studying biomineral-producing microorganisms, factors affecting biomineralization, and the use of this process in biotechnological applications.

This updated and expanded second edition reviews numerous aspects of the marine microbiome and its possible industrial applications. The marine microbiome is the total of microorganisms and viruses in the ocean and seas and in any connected environment, including the seafloor and marine animals and plants. In the first part of the book, diversity, origin and evolution of the marine microorganisms and viruses are discussed. The microbes presented originate from all three domains of life: Bacteria, Archaea, and Eukarya. The second part sheds some light on the different communities: it describes marine habitats and how their inhabitants control biogeochemical cycles. The third part finally examines the microbial ocean as a global system and evaluates methods of utilizing marine microbial resources. Adopting a translational approach, the book connects academic research with industrial applications, making it a fascinating read and valuable resource for microbiologists from both domains.

‘Developmental biology'is widely understood as processes, which mainly concern embryonic animal development and differentiation of cells and tissue. It is also often defined as the timeline for the evolutionary developmental biology of eukaryotic multicellular higher organisms, i.e., plants and animals. The development of prokaryotes and lower eukaryotes in contrary has been neglected for a long time, which was the motivation for publishing this book. This book highlights one of Darwin's most important findings: Evolution is a creative, but not a conscious process. It also illustrates that this concept does not only apply to multicellular higher organisms, but affects every form of life.The reader shall find complex biochemical and genetic pathways of bacteria, yeasts or protozoa, comparable to those exhibited by plants or animals. The molecular mechanisms of dramatic genome rearrangements, recombination and horizontal gene transfer that are responsible for evolutionary adaptations are discussed. Additionally, the book covers bacteria of the genera Myxobacteriales and Caulobacterales, which are able to develop tissue-like cellular organization. The morphogenesis of entomopathogenic fungi and the endosymbiont theory are also addressed. The book is a useful introduction to the field for junior scientists, interested in bacteriology, protistology and fungal development. It is also an interesting read for advanced scientists, giving them a broader view of the field beyond their area of specialization.

This volume presents a comprehensive overview of the latest developments in symbiosis research. It covers molecular, organellar, cellular, immunologic, genetic and evolutionary aspects of symbiotic interactions in humans and other model systems. The book also highlights new approaches to interdisciplinary research and therapeutic applications. Symbiosis refers to any mutually beneficial interaction between different organisms. The symbiotic origin of cellular organelles and the exchange of genetic material between hosts and their bacterial and viral symbionts have helped shaped the current diversity of life. Recently, symbiosis has gained a new level of recognition, due to the realization that all organisms function as a holobiome and that any kind of interference with the hosts influences their symbionts and vice versa, and can have profound consequences for the survival of both. For example, in humans, the microbiome, i.e., the entirety of all the microorganisms living in association with the intestines, oral cavity, urogenital system and skin, is partially inherited during pregnancy and influences the maturation and functioning of the human immune system, protects against pathogens and regulates metabolism. Symbionts also regulate cancer development, wound healing, tissue regeneration and stem cell function. The medical applications of this new realization are vast and largely uncharted. The composition and robustness of human symbionts could make them a valuable diagnostic tool for predicting impending diseases, and the manipulation of symbionts could yield new strategies for the treatment of incurable diseases.

Algae, including cyanobacteria, are in the spotlight today for a number of reasons; firstly it has become abundantly clear over recent years that algae have been neglected in terms of basic research and that knowledge gap is being rapidly closed with the establishment of some surprising discoveries, such as the presence of Near-Infra-Red-Absorbing cyanobacteria and a wealth of natural products; secondly molecular approaches have provided a wealth of approaches to genetically modify algae and produce value-added products; thirdly it has become clear just how important, marine phytoplankton is to global carbon capture and the production of food globally; and fourthly, it has also become clear that algae present unparalleled opportunities to generate biofuels in a sustainable and non-polluting way. This volume presents 15 chapters by world experts on their subjects, ranging from reviews of algal diversity and genetics to in-depth reviews of special algal groups such as diatoms (which account for over 30% of marine carbon capture). Other chapters chart the ways in which this carbon capture occurs or how there are a multiplicity of ways in which algae intercept sun light and deploy this energy for carbon capture. A fascinating aspect here is the way in which sun light is harvested. A special chapter is devoted to the very recent and exciting possibility that algae use coherent light energy transformation to enhance the efficiency of light capture, an aspect of quantum physics that has implications for future developments at several levels and a variety of industries. Just how and why algae use Chlorophyll a as the major light capture pigment is discussed in several chapters. However, attention is also given to those cyanobacteria, which have been found to use the special Near-Infra Red absorbing chlorophylls mentioned above. And attention is also given to those algae that employ phycobiliproteins to fill in the “green window”, i.e., the spectral region from 400 – 650 nm, which is not efficiently covered by chlorophyll and carotenoid pigments. Photoinhibition and photoprotection is the subject area of several chapters and one which it is essential to understand a we work towards greater efficiency of algal photosynthesis. A final chapter is devoted to understanding the molecular basis for coral bleaching, a much-neglected area that is essential in trying to come up with solutions to this very worrying phenomenon, caused by global warming and ocean acidification.This is a book for research scientists, environmentalists, planners in a range of areas including those of marine resources, nutrient control and pollution of water bodies and that growing body of concerned citizens interested in controlling carbon emissions and global warming. Special attention has been given to generating a set of articles that will be read by university students, informed laymen and all those whose wish to understand the rapid changes that have come about in our knowledge of algae over the past decade.

Over the past few decades, chromatin modulation has emerged as an important regulator of gene expression. This second edition provides detailed information on the epigenetic mechanisms in plants, illustrating the value of this research in plants of agronomic importance. It examines recent advances regarding plants'epigenetic regulation in response to abiotic and biotic types of stress; the epigenetic basis of plant immunity; evolution and functions of plant histones; epigenetic variation and plant breeding; and epigenome editing and crop improvement. The content is intended to promote the development of future biotechnologies to manipulate and selectively activate/inhibit proteins and metabolic pathways to counter pathogens, to treat important diseases, and to increase crop productivity. The development of new fields, like epigenome editing and RNA epigenetics, will certainly improve our understanding of currently known epigenetic modifications and their roles in e.g. host-pathogeninteractions, crop productivity, and in response to environmental stimuli. This volume contains twelve new/revised chapters, written by an international team of experts on plant epigenetics, and addresses the needs of researchers and professionals in the fields of agronomics, crop breeding, epigenetics, plant biochemistry, plant developmental biology, and related disciplines.

Animal evolution has always been at the core of Biology, but even today many fundamental questions remain open. The field of animal ‘evo-devo'is leveraging recent technical and conceptual advances in development, paleontology, genomics and transcriptomics to propose radically different answers to traditional evolutionary controversies. This book is divided into four parts, each of which approaches animal evolution from a different perspective. The first part (chapters 2 and 3) investigates how new sources of evidence have changed conventional views of animal origins, while the second (chapters 4–8) addresses the connection between embryogenesis and evolution, and the genesis of cellular, tissue and morphological diversity. The third part (chapters 9 and 10) investigates how big data in molecular biology is transforming our understanding of the mechanisms governing morphological change in animals. In closing, the fourth part (chapters 11–13) explores new theoretical andconceptual approaches to animal evolution. ‘Old questions and young approaches to animal evolution'offers a comprehensive and updated view of animal evolutionary biology that will serve both as a first step into this fascinating field for students and university educators, and as a review of complementary approaches for researchers.

This book presents the latest advances in rice genomics, genetics and breeding, with a special focus on their importance for rice biology and how they are breathing new life into traditional genetics. Rice is the main staple food for more than half of the world's population. Accordingly, sustainable rice production is a crucial issue, particularly in Asia and Africa, where the population continues to grow at an alarming rate. The book's respective chapters offer new and timely perspectives on the synergistic effects of genomics and genetics in novel rice breeding approaches, which can help address the urgent issue of providing enough food for a global population that is expected to reach 9 billion by 2050.

This book presents 19 selected contributions to the 20th Evolutionary Biology Meeting in Marseille, which took place in September 2016. They are grouped under the following major themes:· Self/Nonself Evolution· Species Evolution and Evolution of Complex Traits· Methods and Concepts The aims of the annual meetings in Marseille – which bring together leading evolutionary biologists and other scientists using evolutionary biology concepts, e.g. for medical research – are to promote the exchange of ideas and to encourage interdisciplinary collaborations. Offering a revealing overview of the latest findings in the field of evolutionary biology, this book represents an invaluable source of information for scientists, teachers and advanced students alike.

This book presents, in 26 chapters, the status quo in epigenomic profiling. It discusses how functional information can be indirectly inferred and describes the new approaches that promise functional answers, collectively referred to as epigenome editing. It highlights the latest important advances in our understanding of the functions of plant epigenomics and new technologies for the study of epigenomic marks and mechanisms in plants. Topics include the deposition or removal of chromatin modifications and histone variants, the role of epigenetics in development and response to environmental signals, natural variation and ecology, as well as applications for epigenetics in crop improvement. Discussing areas ranging from the complex regulation of stress and heterosis to the precise mechanisms of DNA and histone modifications, it presents breakthroughs in our understanding of complex phenotypic phenomena.

This book summarizes recent advances in understanding the functions of plant and algal lipids in photosynthesis, in development and signaling, and in industrial applications. As readers will discover, biochemistry, enzymology and analytical chemistry, as well as gene knock-out studies have all contributed to our rapidly increasing understanding of the functions of lipids. In the past few decades, distinct physical and biochemical properties of specific lipid classes were revealed in plant and algal lipids and the functional aspects of lipids in modulating critical biological processes have been uncovered. These chapters from international authors across relevant research fields highlight the underlying evolutionary context of lipid function in photosynthetic unicellular and multicellular organisms. The book goes on to encompass what lipids can do for industrial applications at a time of fascination with plants and algae in carbon fixation and as sources for production of food, energy and novel chemicals. The developmental context is a part of the fresh and engaging perspective that is presented in this work which graduate students and scientists will find both illuminating and useful.

The genome is more than a linear code as depicted by its DNA sequences as several interacting factors play a crucial role in shaping its organization and function. The complete sequences of a number of plant genomes and the recent advances of high-throughput technologies has fueled research efforts in the field of Plant Nuclear Biology unveiling numerous insights about the mechanisms underlying genome regulation. Genomic information is being integrated into molecular- and cellular-level mechanisms of the plant processes. A host of nuclear processes underlie key developmental processes as well as biotic and abiotic interactions. Non-coding RNAs have been increasingly recognized as players in gene expression and genome defense and integrity. However, in vivo, genomes exist as elaborate physical structures, and their functional properties are strongly determined by their cellular organization. Various types of subcellular structure have been identified in the nucleus, which are associatedwith transcription factors, RNA processing proteins and epigenetic regulators. Interestingly, these nuclear bodies display different behaviors in response to the environment. This book compiles a series of landmark discussions of the recent advances in plant nuclear biology research focusing in the functional relevance of the arrangement of genomes and nuclear processes that impact plant physiology and development.

This volume offers a much-needed compilation of essential reviews on diverse aspects of plant biology, written by eminent botanists. These reviews effectively cover a wide range of aspects of plant biology that have contemporary relevance. At the same time they integrate classical morphology with molecular biology, physiology with pattern formation, growth with genomics, development with morphogenesis, and classical crop-improvement techniques with modern breeding methodologies. Classical botany has been transformed into cutting-edge plant biology, thus providing the theoretical basis for plant biotechnology.It goes without saying that biotechnology has emerged as a powerful discipline of Biology in the last three decades. Biotechnological tools, techniques and information, used in combination with appropriate planning and execution, have already contributed significantly to economic growth and development. It is estimated that in the next decade or two, products and processes made possible by biotechnology will account for over 60% of worldwide commerce and output. There is, therefore, a need to arrive at a general understanding and common approach to issues related to the nature, possession, conservation and use of biodiversity, as it provides the raw material for biotechnology. More than 90% of the total requirements for the biotechnology industry are contributed by plants and microbes, in terms of goods and services. There are however substantial plant and microbial resources that are waiting for biotechnological exploitation in the near future through effective bioprospection. In order to exploit plants and microbes for their useful products and processes, we need to first understand their basic structure, organization, growth and development, cellular process and overall biology. We also need to identify and develop strategies to improve the productivity of plants.In view of the above, in this two-volume book on plant biology and biotechnology, the first volume is devoted to various aspects of plant biology and crop improvement. It includes 33 chapters contributed by 50 researchers, each of which is an expert in his/her own field of research. The book begins with an introductory chapter that gives a lucid account on the past, present and future of plant biology, thereby providing a perfect historical foundation for the chapters that follow. Four chapters are devoted to details on the structural and developmental aspects of the structures of plants and their principal organs. These chapters provide the molecular biological basis for the regulation of morphogenesis of the form of plants and their organs, involving control at the cellular and tissue levels. Details on biodiversity, the basic raw material for biotechnology, are discussed in a separate chapter, in which emphasis is placed on the genetic, species and ecosystem diversities and their conservation.Since fungi and other microbes form an important component ofthe overall biodiversity, special attention is paid to the treatment of fungi and other microbes in this volume. Four chapters respectively deal with an overview of fungi, arbuscularmycorrhizae and their relation to the sustenance of plant wealth, diversity and practical applications of mushrooms, and lichens (associated with a photobiont). Microbial endosymbionts associated with plants and phosphate solubilizing microbes in the rhizosphere of plants are exhaustively treated in two separate chapters. The reproductive strategies of bryophytes and an overview on Cycads form the subject matter of another two chapters, thus fulfilling the need to deal with the non-flowering Embryophyte group of plants.Angiosperms, the most important group of plants from a biotechnological perspective, are examined exhaustively in this volume. The chapters on angiosperms provide an overview and cover the genetic basis of flowers development, pre-and post-fertilization reproductive growth and developme

This volume offers an up-to-date overview of biotechnologically oriented barley research. It is structured into two major sections: the first focusing on current agricultural challenges and approaches to barley improvement, and the second providing insights into recent advances in methodology. Leading scientists highlight topics such as: the global importance of barley; genetic diversity and genebanks; domestication; shoot and inflorescence architecture; reproductive development; mineral nutrition; photosynthesis and leaf senescence; grain development; drought tolerance; viral and fungal pathogens; phytophagous arthropods; molecular farming; sequence resources; induced genetic variation and TILLING; meiotic recombination; Hordeum bulbosum; genome-wide association scans; genomic selection; haploid technology; genetic engineering; and whole plant phenomics. Providing comprehensive information on topics ranging from fundamental aspects to specific applications, this book offersa useful resource for scientists, plant breeders, teachers and advanced students in the fields of molecular and plant cell biology, plant biotechnology, and agronomy.

This book provides a comprehensive coverage of the advances in genetics and genomics research on rice. The chapters feature the latest developments in rice research and cover such topics as the tools and resources for the functional analysis of rice genes, the identification of useful genes for rice improvement, the present understanding of rice development and biological processes, and the application of this present understanding towards rice improvement. The volume also features a perspective on synthesis and prospects, laying the groundwork for future advances in rice genetics and genomics.Written by authorities in the field, Genetics and Genomics of Rice will serve as an invaluable reference for rice researchers for years to come.

The purpose of this book is to provide an up to date review of the nature and consequences of epigenetic changes in cancer. Epigenetics literally means “above” genetics, and consists of heritable gene expression or other phenotypic states not accounted for by DNA base sequence. Epigenetic changes are now known to make a large contribution to various aspects of tumorigenesis. These changes include alterations in global and promoter specific DNA methylation, activating and repressive histone modifications, and changes in higher order chromatin structures. Each of these topics will be covered in this book.

We characterize an isolated molecule by its compos~t~on, i.e. the number and types of atoms forming the molecule, its structure, i.e. the geometrical arrangement of the composite atoms with respect to each other, and its possible, i.e. quantum mechanically allowed, stationary energy states. Conceptually we separate the latter, being aware that this is an approximation, into electronic, vibrational and rotational states, including fine and hyperfine structure splittings. To be sure, there is an intimate relation between molecular structure and molecular energy states, in fact it is this relation we use, when we obtain structural information through spectroscopy, where we determine transitions between various stationary states of the molecule. The concepts above have proven extremely useful in chemistry and spectroscopy, however, the awareness of the limitations of these concepts has grown in recent years with the increasing recognition of (i) fluctional molecules, (ii) multiphoton absorption processes and (iii) influences due to the surroundings on'isolated'molecules.